Chucks are employed to support wafers in a variety of semiconductor workpiece processes. In a deposition process, for example, a chuck clamps a semiconductor wafer in place while a film is deposited on the wafer. Similarly, in an etch process, an electrostatic chuck clamps a semiconductor wafer in place while material is removed from the wafer. An electrostatic chuck has electrodes that are energized with a clamping voltage, which electrostatically clamps the wafer to the surface of the electrostatic chuck.
After a wafer is transferred to a processing chamber, it rests on the upper surface of the electrostatic chuck. A clamping voltage is applied to the electrostatic chuck to clamp the wafer during the process. Uniformity in the chuck surface is critical to deposition or etch uniformity across the wafer surface. Over a period of use, uneven wear on the chuck can lead to poor uniformity across a wafer, as well as poor wafer-to-wafer uniformity.